Tor Network Anonymity Research And Routing Algorithm Improvement

The Second Generation Onion Router(Tor)is the most popular low latency anonymous communication system with the largest group of anonymous users.As a distributed network based on volunteers,the Tor network is vulnerable to network attacks,which leads to the reduction of user anonymity.Due to the unified link construction algorithm,the Tor network can not meet the various needs of users.Aiming at these two problems of the Tor network,this paper carries out research.This paper collects the historical data of onion routers and makes statistical analyses.On this basis,based on the former Tor network anonymity estimation formulas,we research them from two aspects of router bandwidth and router label.First of all,this paper improves the weighted bandwidth anonymity estimation formula proposed by predecessors,gives the theoretical derivation process of the formula,and verifies the correctness of the anonymity formula through comparative experiments.Secondly,according to the uneven distribution of router node labels in the Tor network,a Gini coefficient anonymity estimation function based on node labels is proposed.Theoretical analysis is given,and the correctness of the anonymity formula is verified by statistical experiments.This paper reviews the research progress of improved routing algorithms in the Tor network.A dynamic routing algorithm based on bandwidth-weighted random selection is proposed to improve the compromise between user anonymity security and network performance.By setting dynamic parameter which can be controlled by the user,the algorithm realizes the user's personalized setting during the network link construction.Through the simulation experiment of running link establishment,it is proved that the improved algorithm realizes the dynamic selection of nodes in the circuit and can meet the needs of different users for higher performance or higher anonymity.In this paper,the improved routing algorithm is implemented by modifying the Tor network source code.The improved Tor network source code is tested by the Shadow emulation platform.The test results show that the improved algorithm achieves the diversity of bandwidth selection,completes the dynamic link construction,and supports the different needs of clients.Based on the improved routing algorithm,an instant messaging client application system is developed.This paper introduces the application system from system requirement analysis,outline design,functional module design,and so on.Finally,the function test of the instant messaging system is carried out.